


The Tail of Quirks

by rockolore



Category: Dragon Ball, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: BAMF Midoriya Izuku, Dragon Ball AU, Dragon Ball Z - Freeform, Izuku has a Saiyan quirk, Midoriya Izuku Does Not Have One for All Quirk, Midoriya Izuku Has a Quirk, Parental Aizawa Shouta | Eraserhead, thats it, thats the fic
Language: English
Status: In-Progress
Published: 2020-07-25
Updated: 2020-09-12
Packaged: 2021-03-05 20:55:09
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,559
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25501708
Author URL: https://archiveofourown.org/users/rockolore/pseuds/rockolore
Summary: Midoriya Izuku is born with a tail and a piercing cry.The boy grows up to be exceptionally strong, and after a head injury, friendly and maybe a little insecure. He applies for UA, determined to be a hero and use his strength to help others.This is my self indulgent Dragon Ball AU for BNHA. In my opinion, if you grew up as a child watching Dragon Ball, you probably enjoyed BNHA. First time writer, long time reader.
Comments: 4
Kudos: 19





	1. Chapter 1

Midoriya Izuku was born with a tail.  
The doctor and nurses in the room assured Inko it was a manifestation of a mutant-type quirk, but as the boy grew a few years older, it seemed the only result of his quirk was the tail. The tail, and the temper.  
Izuku screamed and cried when he didn’t get his way, he was aggressive at times and could be known to use his sharper than normal teeth to rip into things.  
Inko took everything day by day, she was caring and patient to her son. She seldom took him out shopping or to play, except for with Bakugou Katsuki, her best friend’s kid. They had similar tempers, and would get into tussles, but were always friends at the end of the day.  
One afternoon, right after Izuku learned how to walk and was confident enough to break away from his mother, he toddled away from her and waddled towards a back alley.  
Inko became distressed when she noticed the boy missing and started asking the shop goers around her if they had seen a young boy. A baggy eyed underground hero noticed her anxiety and overheard her situation. He helped her look and ask around.  
As his mother searched for him, Izuku waddled further away and came upon a man in a dark cloak. The boy turned his fear into anger and snarled at the man.  
“Fiesty tike, huh?” The dark man said, seeming to be wrapped in shadows.  
Izuku responded by glaring at him and grabbing the end of the cloak, chomping into it with his sharp teeth.  
The man chuckled. “Now, now, no need little one. You could be interesting to have around.” He said, and pondered over the boy for a moment, “I sense a deep power in you.” The man started to grab for Izuku, he reached down but pulled back when his hand got caught by the teeth of the boy as well.  
“Well, we might have to do this the hard way-“ The man started to activate one of his quirks as the young Aizawa Shouta ran into the alley, deactivating the man as his hair raised and his eyes pierced through him.  
“Step away.” He said.  
The man glanced behind Aizawa, where he could see more onlookers in the street, attention brought to the scene by the distressed mother and young hero.  
The man paused and took a moment to reach a conclusion. “I guess I will go, I won’t waste my time here.” He addressed Izuku, “I’ll meet you in another time young one.” With that he stepped into the shadows, seeming to disappear as Aizawa inspected where he went after he vanished.  
Inko grabbed her boy and spoke to Aizawa with tears streaming down her face, “Thank you so much! You saved him.”  
“It’s no issue, I’m a hero in training. I am concerned, however, about what he said to your son.”  
Aizawa helped Inko report what happened to the police, but he left her with the phone number he uses for hero work anyway, concerned and intrigued with the family of two. The man parted ways with Inko that day, after many thanks from her and the promise to call if anything happened with her or her son again. From time to time, she would send a care package to his agency with homemade food and nice notes, as thanks for that day.  
A couple years later, Inko took the 3 year old boy on a road trip to see a family member who lived far away and had gotten sick. She stopped miles away from Musutafu in a forest to spend the night in her car. For the first time in his semi-sheltered life, Izuku looked up at the night sky and locked his eyes onto the full moon.  
The transformation was instantaneous, the toddler grew in size and changed in appearance. Inko startled and then grew more and more scared of what was happening to her baby. Soon Izuku stood as tall as a building, in the form of a giant ape, rampaging and barely missing his mother in his blind fury. In terror, Inko hopped into her car and sped away from his immediate vicinity, but could not leave her boy behind. As she watched her son pull trees from the ground and roar into the night, the only thing the woman could think to do was to call Aizawa, as she still had the old contact in her phone. She rung him up and he answered on the third ring, sounding tired and flustered.  
“Hello?” His voice crackled through, Inko barely having service. “Mrs. Midoriya, what’s wrong, did something happen?”  
“Eraserhead, my son, something hap-happened to him. He-he, he’s turned into something else, it must be his quirk, please.”  
Aizawa could hear the groans of the forest, cracking and smashing, through the receiver. He knew it was an emergency if Inko has called. It was the first time since he had given her his number. The tired underground hero got the location of the Midoriyas’ through his phone and proceeded to try to contact any kind of quick transportation he could find.  
There ended up being a hero connection with a teleportation quirk that came to Aizawa through some other underground heroes. He had to be able to visualize a place and situation before sending someone there, with a ten minute cut-off of how long a person was able to stay in that place. Aizawa showed him what he could, some satellite images of the approximate place, and the location he got from his phone. Within a minute he was there, and could hear, but not yet see, the commotion that the boy was causing.  
Aizawa sent a quick text to Midoriya, assuring her that he was now on scene, as had been sending her updates. He then scaled a tall tree to get a better view of the situation. As soon as he got to the top he was astonished at what he saw. He was a half mile out, but could see the cause of the earth’s rumbling. It was hard to believe that this was the kid that he got regular photos of from Mrs. Midoriya’s care packages, but he could see in the pale moonlight that the beast had the same fur color as the green mop on the kid’s head, and the same inner rage he seemed to have.  
Aizawa devised a plan to get closer so he could use his quirk on the kid, but he only had so much time to get to him. He started jumping from tree to tree, using the parkour he learned from scaling buildings to fight criminals. As he got closer and closer the ground shook more and an increasing volume of projectiles were flung around him, making climbing the trees more dangerous. When he was only 100 feet out, he knew he only had a little time to get a handle of the situation.  
He made sure he was out of sight, dashing quickly in the forest’s underbrush and around the wreckage of the torn trees before he was close enough to use his quirk on the boy. He got his capture weapon ready to catch him and activated his quirk to relinquish the boy of the affects of his quirk.  
Just as he made contact with Izuku and saw as he started shrinking, the 10 minute timer ticked down the last couple of seconds Aizawa had, and rung as Aizawa was teleported away before he could assure of the boy’s safety.  
Inko has been watching everything with rapt attention, her anxiety and stress levels through the roof as she watched Aizawa come upon her boy. She watched as he turned Izuku back to normal, just to disappear. She saw the dot of her son, falling to the ground but could do nothing as she saw him hit his head on one of the limbs of the tree. She was already driving when she saw Aizawa disappear, at the ready to jump into the situation to grab her son. She screeched into the area, and barely stopped the car before running to Izuku and checking him over. Aside from the large bump on his head, he didn’t seem to be otherwise injured, but Inko was scared to move him in fear of making any internal things worse. She called the ambulance, but was advised that one had already been called and was on the way. She then got a call from Eraserhead.  
“Hello?! Mrs. Midoriya is he ok? I am so sorry, I didn’t reali-“  
Inko cut him off, “I think he’ll be ok, Eraserhead. Thank you so much, you’ve saved my son again.”  
Her tears welled up and spilled over, her body was wrecked by the stressful event, and she couldn’t hold it in any longer.  
Aizawa heard her sniffling on the phone, he was back in the room with the teleport quirk man, trying to remedy the situation. He blamed himself for what happened, he should’ve known and been quicker, if he had been, the boy would not have gotten hurt.  
“”I’m glad Mrs. Midoriya, but please know that I am very sorry, I hope he will be ok.” The tired hero hung up the phone and bowed his head, he was more exhausted after that intense couple of minutes, and needed to take the rest of the night off to calm his nerves. He was young, only a couple of years into being a hero, and had done many things that he regretted. This one would be at the top of his list, he knew.

Inko sat with her son, smoothing down his hair and cupping his face as she waited for the helicopter to arrive that would take him quickly to the hospital. She was still shocked from the situation and could not begin to worry about how this would affect her raising of Izuku front his point forward. She only knew that, as had been true every moment raising him up until then, she would love and care for him no matter what.


	2. Chapter 2

**Summary for the Chapter:**

> What happens after the event in the forest?

Despite her son turning into a giant, ruthless ape, the most surprising thing that came from the event was the change in Izuku’s personality. He woke up slowly, but when he was fully conscious the change was startling. The first instance of difference came when he hugged her, only a couple of hours after waking. He had seldom before shown that level of affection. She hugged him and patted his back, surprised, but basking in this new love.  
He was ejected from the hospital, the doctor assuring Inko that he was completely healed and everything appeared fine, both internally and externally.   
From that point forward Izuku was a changed child. He was more sensitive and less fussy. One thing never changed though, he never backed down from a fight. Inko had to rush to keep him from danger often, if it was a tussle with the neighbor’s kids over a stolen toy or trying to get him out of a too-tall tree he had climbed, using his tail for further dexterity.   
The tail was another thing entirely. He could use it as well as if it were another arm, but as soon as it was pulled or injured he was rendered motionless. Bakugou used this exploitation to his heart’s content, forcing Izuku to learn to make his tail stronger or deal with the effect that pulling had on it.  
Another change that came after the event in the forest was that Aizawa became more a part of the small family’s life. Every full moon after he was seen in the Midoriya household, making sure he was near in case another event like the first one never happened again. He grew closer to the family, Inko insisted that he have home-cooked dinner and a nice place to rest if he needed it.  
Izuku grew older with this dynamic, the young pro hero being close to him and his mother. He understood that looking at the moon could cause some great event, but never paid too much mind to the outcomes of his quirk, he was more invested in other things. Other things like fighting. Izuku loved to practice fight, his favorite heroes were the strongest ones, and of course that included All Might with his immense power. He would sit in front of the computer and mock fight with the hero on screen, throwing a punch when he did and successfully learning the moves. Inko eventually gave in to her son's love for fighting and enrolled him in martial arts when he was 5. Izuku was a prodigy in the class, he rose through the ranks quickly and learned several offshoots. With the monthly visits from Aizawa, the kid finally convinced him to be his teacher as well, and Aizawa started training him on the side. So Izuku trained his tail and trained himself, always with that yearning for a battle and a win, and the words of the shadowed man were never forgotten by Aizawa, who kept a close eye on him.  
***  
Izuku almost ran out of his training session with his excitement to meet up with Aizawa, his instructor was finally going to let him play with his capture weapon and maybe, with some pleading from the boy, teach him how to use it. Izuku was 14 and finishing Junior High at this point, he used his tail to close the door behind him as he waved everyone in the dojo goodbye. It was the same place that he had initially been enrolled in by his mother and he was somewhat of a star student. A huge amount of his success could be attributed to his immense strength, only rising through the years alongside his tenacity.  
As he ran out into the sidewalks surrounding the building he almost ran into another student of the dojo, Ojiro Mashirao. Ojiro stopped him and placed his hands on his shoulders, righting him from the near-collision. Izuku continued to run in place and huffed at the sudden stop to the journey to his destination.  
“Hey Midoriya, I’ve got to ask again, have you thought about applying to U.A.?” The taller boy inquired. It was a common topic between the two boys. They’d both gone to the dojo for as long as they could remember and had a bond over being “tail brothers”.  
“I don’t know, hadn’t thought about it too much. But I got to go Mashirao, I’ll catch up later!” Izuku rushed through his words, glancing over Ojiro’s shoulder.  
Ojiro sighed, used to Izuku’s antics by this point, and turned his and Izuku’s body, letting the boy go with a little push that jump-started him to his destination. It was as if nothing had momentarily stopped Izuku’s journey as he kept going just as fast as he had when he was leaving.  
Izuku ducked and ran through the streets, he and Aizawa had scheduled their meetups this way, right after Izuku’s training at the dojo ended, they would meet up before the pro hero started his patrol for the night. They trained in an older warehouse, it was used as a meetup spot for underground heroes, but the building was big enough to train in and close enough to both Izuku’s dojo and house that it was the perfect spot for them. Their training sessions usually included disguised hero lessons from Aizawa, because although the boy was interested in heroes and quirks, he was mostly interested in the strength aspect. He was not completely infatuated with the idea of being a hero yet, but Aizawa knew that all he needed was some sort of push. All his previous attempts were not the most helpful for some reason. Izuku liked to learn from Aizawa though, they would mock fight, Izuku holding back some strength in order to fight, and Aizawa teaching him the control he needed to not over-exert himself or cause destruction.  
When Izuku arrived in the main room of the warehouse, Aizawa was already waiting with one of his extra capture weapons. Izuku got excited and practically jumped to the pro hero’s location, using grabby hands towards the scarf.  
“Wow, Aizawa! I’m so excited, please please pleeeaase teach me some cool tricks.” Izuku said this as he methodically wrapped himself with the capture weapon, as he had seen Aizawa do so many times before.   
Aizawa couldn’t help being constantly impressed by the boy, he had always caught onto things very quickly, but the way the boy was handling the scarf was evidence of how his brain tracked and remembered these kinds of things. Aizawa replied, “It seems like you’ve already picked up something, how about you show me what you think can be done with it.”  
Izuku took that as a challenge, Aizawa saw a glint in his eyes before he took one end of the scarf and started to get the hang of how it could be used. Within moments he was relaxed enough with it that he was attempting to grab Aizawa with it, running after him with glee and surprising precision. Aizawa, taken off guard, rolled his eyes, and started taken the situation back into his control. Although Izuku was a prodigy, he didn’t have the older man’s years of expertise. He tripped up Izuku with his own scarf, using Izuku’s amateur movements to bring him down. Izuku sat for a second, head down and thinking, until he bounced back up, as willing as ever to learn and doing so at a rapid pace. Aizawa could already see that his stance had shifted and adapted to the new weight the capture weapon brought. The underground hero resigned himself to a night of this, teaching the boy in this way always brought rounds and round of practice fighting until Aizawa finally had to leave to do his hero work. Despite knowing what his night would entail, a small smile came upon Aizawa’s face under the capture weapon. He wouldn’t admit it, but he loved this time with Izuku, he loved the way his brain adapted and it was constantly intriguing him. Since that day when Izuku was very young, he knew the boy would be a problem child but Aizawa had grown very attached to the monkey boy nonetheless.  
Hours later Izuku was walking home from the training session. He hadn’t been able to convince Aizawa to give him the capture weapon, the underground hero too convinced that he would get into trouble with it. Izuku wrapped his tail around his waist like a belt and thought about was Mashirao had said. It was becoming the time that the students were encouraged to pick where they were planning to go for high schools and taking the placement tests. Izuku hadn’t yet filled out the form, and he knew that both Kacchan and Mashirao were planning on going to U.A.. His tail unwrapped from his waist and swung idly in the air as he thought about his options, he did want to stick with his childhood friends, but he just didn’t think he had the drive to be a hero that his friends did. He was interested in them and in quirks, he had his journals he wrote about battle strategy, but he just couldn’t compare his interest in fighting to the dreams that his friends had about becoming heroes.   
He crossed his arms behind his head and looked up at the night sky. It was almost to the point of being the full moon, just a couple of days off. Izuku looked away quickly, the moon did something to his heart, and made his skin itchy with some kind of need. He never wanted to become the monster his mother spoke of in hushed whispers. The moon always gave him this feeling of restlessness, and it bothered him that something could affect him in that way. He was comforted by the appearance of his apartment building marking an end to his walk home. When he got inside he took off his shoes and handed his jacket off to his tail to hang on the coat rack. he padded into the kitchen where his mother was sitting with dinner already made, predicting the time when he was getting home with an accuracy only learned by years of practice. Izuku happily sat down and chowed in, he ate like a starved man, as he always did. His mother always had enough food made for him though, comparable to a small army, especially as near to the full moon that they were. Inko had taken her son’s appetite in stride, just like everything else about him. She gave him a hug and asked about his day, relishing in the attention he gave her as he told her about his training session with Aizawa. He asked about her day as well, listening as she told him about the thralls of being a receptionist in a hospital. When he was done with his meal they watched an old fighting movie together before going to bed.  
As Izuku was falling asleep he had one last fleeting thought about high schools, he drowsily decided he wouldn’t decide until there was some sort of sign to go one way or another.

**Notes for the Chapter:**

> Hello! I'm going to write this whenever I feel like it, it kind of takes a while because I'm still getting used to this whole fanfiction writing thing. but give me tips or whatever if you want to! Thanks for reading, and thanks for the kudos and comments so far!!

**Author's Note:**

> Thanks for reading! This is my first fic and I’m super excited about the concept. This was inspired by the many “Izuku has a quirk, what happens then?” Fics that I love so much!


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